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DataToolings

JSON to Protobuf Schema Converter

Convert JSON objects to Protocol Buffers (proto3) schema definitions. Handles nested objects, arrays, and all scalar types automatically.

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What Is a JSON to Protobuf Converter?

Protocol Buffers (protobuf) is Google's language-neutral binary serialization format. A JSON to Protobuf converter reads a JSON object and generates a .proto schema file with proto3 syntax — including nested message types for every nested object in your JSON.

How to Use

  1. Paste your JSON object into the left textarea.
  2. Set a root message name (default: Root) and package name.
  3. The proto3 schema is generated automatically as you type.
  4. Click Copy to copy the schema and save it as a .proto file.

Features

  • Generates proto3 syntax with correct scalar types: string, bool, int64, double.
  • Handles nested objects as separate named message types.
  • Arrays are converted to repeated fields automatically.
  • Configurable root message name and package declaration.
  • Runs entirely in your browser — no data is sent to any server.

FAQ

What proto syntax version does this use?

This tool always generates proto3 syntax, which is the current recommended version. Proto3 removes required/optional field labels and uses default zero values for unset fields.

How are JSON numbers mapped to proto types?

Integers (e.g. 42) map to int64, and floating-point numbers (e.g. 3.14) map to double. You can manually change these to int32, float, etc. after generation.

What happens with arrays of objects?

Arrays of objects generate a dedicated message type named after the parent message and field (e.g. RootRolesItem), and the field becomes a repeated field referencing that message.